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BDS3 Clinical Endo > Session 2 > Flashcards

Session 2 Flashcards

1
Q

What are the 3 design objectives for endo?

A
  • Create a continuously tapering funnel shape
  • Maintain apical foramen in original position
  • Keep apical opening as small as possible
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2
Q

What are conventional instruments in endo?

A
  • K files
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3
Q

What are K filed made from?

A
  • Stainless steel
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4
Q

What are the 3 possible lengths of K files?

A
  • 21, 25 or 31mm
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5
Q

The handles of K files (ISO instruments) are coloured. What does this mean?

A
  • Coded according to file tip size
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6
Q

What is the % taper of k files?

A

2% taper

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7
Q

What colour is a size 06 K file?

A

pink

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8
Q

What colour is a size 08 K file?

A

Grey

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9
Q

What colour is a size 10 K file?

A

purple

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10
Q

What colour is a size 15 K file?

A

White

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11
Q

What colour is a size 20 K file?

A

Yellow

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12
Q

What colour is a size 25 K file?

A

Red

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13
Q

What colour is a size 30 K file?

A

Blue

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14
Q

What colour is a size 35 K file?

A

Green

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15
Q

What colour is a size 40 K file?

A

Black

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16
Q

What colour is a size 45 K file?

A

White

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17
Q

What colour is a size 50 K file?

A

Yellow

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18
Q

What colour is a size 55 K file?

A

Red

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19
Q

What colour is a size 60 K file?

A

Blue

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20
Q

What colour is a size 70 K file?

A

Green

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21
Q

What colour is a size 80 K file?

A

Black

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22
Q

How long is the cutting flute on a K file (ISO instrument)?

A
  • 16mm
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23
Q
  • Cutting portion:
  • 16mm long
  • The diameter of the working portion of the instrument will increase by 2% over its length
  • Means for every 1mm back from the tip of the instrument the diameter of the instrument will increase by 0.02mm
  • If look over 16mm length - the taper of 0.02% will mean that over the 16mm length the diameter will increase by 0.32mm
  • Important to recognise as will give some indication into what the instruments are kind of doing and also in combination how these instruments might work
A

Example of determining taper and length

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24
Q

K files are flexible, what does this make them useful for?

A
  • Useful in curved canals
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25
Q

When do K files cut?

A
  • When in rotation or cut in a filing motion
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26
Q

What part of the flexible

K files allows them greater flexibility?

A
  • The cross sectional shape (have a square/diamond cross section)
27
Q

What are flexible K files made of?

A
  • Stainless steel or Nickel titanium
28
Q

What motion is used for flexible K files?

A
  • Used in rotation or filing motion
29
Q

Give examples of different types of filing motions? (4)

A
  • Filing
  • Reaming
  • Watch winding
  • Balanced force motion
30
Q

How do you do the watch winding motion?

A
  • Back and forward oscillation of 30-60 degrees

- Whilst applying light apical pressure

31
Q

Which kind of file is effective using the watch winding motion?

A
  • Effective with K files
32
Q

What is the watch winding motion useful for?

A
  • Useful for passing small files through canals
  • Allows instruments to be used with safety, not going to overload the instruments so should therefore move through the canal
33
Q

How does the watch winding motion work?

A
  • What this will do is engage and break dentine, engage and break etc as it moves apically
34
Q

When do we used the balanced force technique?

A
  • Use this as we start to use bigger instruments
35
Q

How do you do the balanced force technique?

A
  • Whilst applying apical pressure we are going to rotate the file in a counter clockwise direction by a degree of rotation bigger than the original clockwise rotation
  • What this does is you engage, apply apical pressure then you rotate anticlockwise maintaining the apical pressure - this breaks the dentine
36
Q

We must use irrigants as it is important that debris does not accumulate in the root canal. What happens if this occurs?

A
  • If this occurs blockages will occur which will prevent you from adequately cleaning and shaping the root canal space
37
Q

How does an irrigant work?

A
  • They create a lubricant for the file to work within the canal, they are a medium in which debris can be suspended after production, the irrigant will disinfect the canal and dissolve organic tissue which remains in the canal
  • When refresh irrigant we flush the debris and this allows us to ensure that the canal is as clean and free of debris as possible
38
Q

What are the objectives of root canal irrigants? (5)

A
  • To disinfect the root canal
  • Dissolve organic debris
  • Flush out debris
  • Lubricate root canal instruments
  • Remove endodontic smear layer
39
Q

To irrigate root canals we use a Leur lock syringe and needle. What is this?

A
  • It has a special cut tip which prevents us from creating a significant pressure within the canal
  • Always important that when the needle is in the canal that it is loose and free to move
40
Q

What should the Leur lock needle always be placed short of?

A
  • Short of working length
41
Q

What gauge is the Leur lock needle?

A
  • 27 gauge endodontic-tipped needle
42
Q

How full should you fill a Leur lock syringe?

A
  • Don’t fill the syringe to the top - a third to a half should be full
43
Q

What are the reasons for producing coronal flaring? (3)

A
  • Avoids hydrostatic pressure in the canal
  • Early removal or heavily contaminated contents
  • Improved straight line access to apical 1/3 (important to reduce stress and strain of the instruments as they work)
44
Q

What are the possible methods of coronal flaring? (3)

A
  • Step-down technique
  • Double-flare technique
  • Crown down pressure less technique
45
Q

The modified double flare technique uses the balanced force technique to…? (3)

A
  • Enlarge/flare the coronal part of the root canal
  • To negotiate the narrower apical part of the canal
  • To flare the apical part of the canal by step-back technique

The aim is to create a continuously tapering, funnelled root canal without forcing debris apically whilst respecting original canal anatomy

46
Q

What do we use a gates-glidden bur for?

A
  • To create coronal flaring
47
Q

What is the shape of the cutting tip of a Gates-glidden bur?

A
  • Teardrop shaped
48
Q

How fast should a Gates-glidden bur be run at?

A
  • Should not be run at high revolutions per minute - they should be run at a relatively low level of about 1000 RPM
49
Q

Which size of Gates-glidden bur should we never use?

A
  • Size 1
50
Q

What sizes of Gates-glidden bur will we typically use?

A
  • Size 2, 3 and 4
51
Q

We should never use a gates-glidden bur beyond a curve. How are these burs designed in case this accidentally happens?

A
  • These instruments are designed to break just below the shank and that allows the tip of the instrument to be retrieved should the instrument break in the canal
52
Q

Where should an apical preparation end?

A
  • Should end at the junction of pulpal and periapical tissue
53
Q

Where should the working length be as close to as possible?

A
  • The CDJ (point at which the root canal becomes the PDL)

- This is usually the narrowest part of the canal - apical constriction

54
Q

How can we determine the corrected working length of a canal? (3)

A
  • Radiographically (length should be 1mm from radiographic apex)
  • Use a sound and reproducible reference point (usually the incisal edge or a cusp tip)
  • Use paralleling technique with film holder
55
Q

The distance of the apical constriction from the radiographic apex varies and is greater in what type of teeth?

A
  • Older teeth with secondary cementum
56
Q

Apart from using radiographs. What is another way of determining the corrected working length?

A
  • By using an electronic apex locator
57
Q

What is a more reliable means of determining corrected working length, radiograph or electronic apex locator?

A
  • EAL
58
Q

How do electronic apex locators work?

A
  • What happens is you place your instrument in the root canal and attach the apex locater to the file and to the lip of the patient
  • A current is then passed through the patient and this is able to determine when you leave the root canal and enter the periodontal ligament space
  • Want to look for the point at which the apex locator tells us we are either in the green band or when we reach the 0
  • When we reach the 0 we know we have touched the PDL (this becomes the 0 reading) which shows us the true length of the canal from coronal reference point to your constriction on the PDL
  • Following this our correct working length would be 0.5-1mm short of the length at which you achieved 0 or in this case the first red band appearing
59
Q

What is paper point length determination?

A
  • Allows you to determine the interface between the wet and the dry
  • Dry the canal using paper points then place the paper point into the root canal and as it touched the PDL we will see blood or tissue fluid
  • This interface here allows to determine from a coronal reference point to the interface the length
  • Then would adjust our preparation to that length
  • May use one or multiple methods
  • Always want to use apex locator
60
Q

Once we have determined the WL we need to create the apical preparation. How would we do this?

A
  • Once we have determined working length we need to create the apical preparation
  • In order to do this what we are going to do is we will have already taken our size 10 and 15 to determine the working length
  • Then going to expand the size at the apical preparation
  • Watch winding, balanced force, up to a size 20 at corrected working length then irrigate
  • Then we are going to use a size 10 file back down to working length - this is called recapitulation - this is going to take a small file down, lift the debris from the canal and ensuring we are not packing debris apically
  • Then need to take size 10 file and jus extend it slightly beyond our estimated working length - this is called patency filing
  • Patency filing prevents the accumulation of debris on the apical portion of the canal
  • Then want to start to expand our apical preparation - using balanced force technique we are going to take a size 25 file to our corrected working length
  • At this point we can start to consider about when we might stop our apical preparation
  • We want to reach at least a size 25 however in order to ensure that we have a sufficient apical preparation to allow good irrigation and debridement we may want to further expand our preparation
  • Going to expand the apical preparation until we feel we have the appropriate diameter
61
Q

How do we determine the size of an apical preparation?

A
  • Size determined by initial size of root canal apex
  • Passive exploration known as ‘gauging’
  • Apical preparation size controversial
  • Usually at least ISO size 25
  • Some advocate 30 and larger to allow irrigation
  • Canal curvature impacts upon what is achievable safely
62
Q

For the mid root preparation what technique would we use?

A
  • The step-back technique
63
Q

Explain the step-back technique?

A
  • See a size 25 file has been taken to corrected working length then going to insert k files that are one size grater in the sequence
  • One mm shorter than corrected working length
  • So the 30 file will be inserted 1mm shorter than the working length etc
  • Means that we start to create these steps
  • These steps will be extended more coronally and eventually the apical preparation the apical taper that we create will join the coronal taper that we created initially with the GG bur
  • Then take our master apical file which will be our 25mm K file and will just make fine motions circumferentially in the canal and this will just smooth these steps giving us a continuously tapering funnel shape with a small apical opening which extends into the coronal portion of the tooth

BDS3 Clinical Endo (6 decks)

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